In the prior art patent literature, several devices relating to flexible mandrel methods are known, e.g.:
U.S. Pat. No. 4,197,079 (Patzner, et al.) describes a flexible core for producing crinkle-free tube bends which is comprised of laminates capable of being shifted against one another corresponding to the tube's inner bending radius. To facilitate handling, the laminates are held together by means of, for example, a length of tube which is movable along the laminates.
U.S. Pat. No. 4,030,871 (Cobb) shows an apparatus for thermoforming plastic parts. The device develops an over-hanging hollow portion, using stacked segments yielding into preselected turned relationship during the thermoforming process.
Currently, mandrels used in assembly and/or curing of materials are required to be extracted after use. Typically, hard or soft mandrels are not reusable after an elevated cure process, or they cannot be extracted over a contoured surface. The use of soft mandrels are easy to extract, but have a high coefficient of thermal expansion (CTE), which alters the dimension of material or part during the cure process. Hard mandrels can be made of low CTE material which controls the part geometry, but cannot be extracted over contoured surfaces unless the mandrel is segmented.